Question

what is the value of b? b = □°

Explanation:

Step1: Identify isosceles - triangle property

Since the two sides of the triangle are equal (marked with red - hash marks), the angles opposite those sides are equal. Let the angle opposite the side with one hash - mark be $\angle V$ and the angle opposite the side with two hash - marks be $\angle U$. In $\triangle VUW$, $\angle V = 39^{\circ}$, and $\angle U=b$.

Step2: Use triangle - angle sum property

The sum of the interior angles of a triangle is $180^{\circ}$. So, in $\triangle VUW$, we have $\angle V+\angle U+\angle W = 180^{\circ}$. Since $\angle V=\angle U$ (isosceles - triangle property), and $\angle V = 39^{\circ}$, then $b = 39^{\circ}$.

Answer:

$39$